HB2012 - List of Keywords (quadrupole)

Paper	Title	Other Keywords	Page
MOP207	Planning for Experimental Demonstration of Transverse Emittance Transfer at the GSI UNILAC through Eigen-emittance Shaping	emittance, coupling, simulation, scattering	57
	C. Xiao, O.K. Kester IAP, Frankfurt am Main, Germany L. Groening GSI, Darmstadt, Germany
	The minimum transverse emittances achievable in a beam line are determined by the two transverse eigen-emittances of the beam. For vanishing interplane correlations they are equal to the well-know rms-emittances. Eigen-emittances are constants of motion for all symplectic beam line elements, i.e. (even tilted) linear elements. To allow for rms-emittance transfer, the eigen-emittances must be changed by applying a non-symplectic action to the beam, preferably preserving the 4d-rms-emittance. This contribution will introduce the concept for eigen-emittance shaping and rms-emittance transfer at an ion linac. A path towards the experimental demonstration of the concept at the GSI UNILAC is presented.

MOP211	1-MW Beam Operation Scenario in the J-PARC RCS	injection, emittance, lattice, controls	68
	H. Hotchi, H. Harada, N. Hayashi, M. Kinsho, P.K. Saha, Y. Shobuda, F. Tamura, K. Yamamoto, M. Yamamoto, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y. Irie KEK, Ibaraki, Japan
	The injection energy of the J-PARC RCS will be upgraded from 181 MeV to 400 MeV in the 2013 summer-autumn period. With this upgraded injection energy, we are to aim for 1 MW design output beam power. In this paper, we discuss beam dynamics issues for the 1 MW beam operation and their possible solutions.

MOP220	Local Compensation-rematch for Major Element Failures in the C-ADS Accelerator	cavity, solenoid, emittance, focusing	102
	B. Sun, Z. Li, J.Y. Tang, F. Yan IHEP, Beijing, People's Republic of China
	In order to achieve the required reliability and availability for the C-ADS accelerator, a fault tolerance design is pursued. The effects of cavity failure in different locations have been studied and the schemes of compensation by means of local compensation have been investigated. After one cavity failure, by adjusting the settings of the neighboring cavities and the focusing elements to make sure that the Twiss parameters and energy are approximately recovered to that of the nominal ones at the matching point. We find the normalized RMS emittance and emittances including 99.9% and 100% particles have no obvious growth after applying the compensation with the RMS rematching in each section of the main linac. However, the conclusions above are drawn from the simulation results with the TraceWin code, which doesn't consider the phase difference. A code based on Matlab is under developing. By applying the code on the cavity failure in the middle part of spoke021 section, a fully compensated scheme with good dynamics results is obtained. The space charge effect is still not implanted in the code, and further study and optimization of the code will be performed in the next step.

MOP229	Design of the MEBT1 for C-ADS Injector II	emittance, DTL, rfq, simulation	115
	H. Jia, Y. He, S.C. Huang, C.L. Luo, M.T. Song, Y.J. Yuan, X. Zhang IMP, Lanzhou, People's Republic of China
	The MEBT1 of Chinese ADS Injector II is described. It transports a 2.1 MeV, 10 mA CW proton beam through a series of 7 quadruples and two buncher cavities from the RFQ to the superconducting DTL. For emittance preservation, a compact mechanical design is required. Details of the beam dynamics and mechanical design will be given.

MOP235	Medium Energy Beam Transport Design Update for ESS	cavity, linac, DTL, rfq	128
	I. Bustinduy, F.J. Bermejo, A. Ghiglino, O. González, J.L. Muñoz, I. Rodríguez, A. Zugazaga ESS Bilbao, Bilbao, Spain B. Cheymol, M. Eshraqi, R. Miyamoto ESS, Lund, Sweden J. Stovall CERN, Geneva, Switzerland
	The major challenge of this part of the accelerator is to keep a high quality beam, with a pulse well defined in time, a low emittance and a minimized halo, so that the beam losses downstream the linac be limited and the overall ESS reliability be maximized. In order to minimize beam loss at high energy linac, and the consequent activation of components, a fast chopping scheme is presented for the medium energy beam transport section (MEBT). The considered versatile MEBT is being designed to achieve four main goals: First, to contain a fast chopper and its correspondent beam dump, that could serve in the commissioning as well as in the ramp up phases. Second, to serve as a halo scraping section by means of two adjustable blades. Third, to measure the beam phase and profile between the RFQ and the DTL, along with other beam monitors. And finally, to match the RFQ output beam characteristics to the DTL input both transversally and longitudinally. For this purpose a set of ten quadrupoles is used to match the beam characteristics transversally, combined with two 352.2 MHz buncher cavities, which are used to adjust the beam in order to fulfill the required longitudinal parameters.

MOP238	Beam Position Monitor System of the ESS Linac	linac, LLRF, controls, target	133
	H. Hassanzadegan, A. Jansson ESS, Lund, Sweden A.J. Johansson Lund University, Lund, Sweden
	The pulsed ESS linac will include about 100 BPMs, mostly with a European XFEL style button design, 6 BPMs with a special design for the Medium Energy Beam Transport, as well as 8 stripline BPMs foreseen for the Drift Tubes. The required accuracy and resolution of the position measurement are 100 μm (rms) and 20 μm (rms) respectively with the 50 mA 2.86 ms nominal pulse. In addition to the position measurement, the BPM system needs to measure the beam phase in the nominal pulse as well as several diagnostics pulse modes with a minimum duration and intensity of 5 μs and 5 mA respectively. After a study of the possible electronics platforms, MTCA.4 is now considered as the main prototyping platform for the high performance sub-systems at ESS. It is foreseen to prototype a Rear Transition Module for IQ-based RF signal measurements intended for both the BPM and LLRF systems. The requirements and specifications of the BPM system are presented and the plan for the continuation of the project is described in this paper.

MOP243	Experimental Results of Beam Halo at IHEP	simulation, rfq, space-charge, beam-transport	151
	H.F. Ouyang, T. Huang, J. Li, J. Peng, T.G. Xu IHEP, Beijing, People's Republic of China
	Space-charge forces acting in mismatched beams have been identified as a major cause of beam halo. In this paper, we describe the beam halo experimental results in a FODO beam line at IHEP. With this beam transport line, experiments are firstly carried out to determine the main beam parameters at the exit of a RFQ with intense beams, and then the measured beam profiles at different positions are compared with the multi-particle simulation profiles to study the formation of beam halo. The maximum measured amplitudes of the matched and mismatched beam profiles agreed well with simulations. Details of the experiment will be presented.

MOP260	Beam Halo Measurements using Adaptive Masking Methods and Proposed Recent Halo Experiment	injection, space-charge, diagnostics, simulation	215
	H.D. Zhang, B.L. Beaudoin, S. Bernal, R.B. Fiorito, R.A. Kishek, K. Řežaei, A.G. Shkvarunets UMD, College Park, Maryland, USA
	Beam halo is a common phenomenon in particle beams, especially for modern, advanced accelerators where high beam intensities lead to strong space charge. Halo is generally understood as a population of particles that do, or will, reach large transverse radii relative to a more intense, centralized beam core. It is associated with emittance growth, beam quality degradation and particle loss. The particle-core model [1] is commonly used to describe halo formation as the result of a parametric resonance due to envelope mismatch. Few experiments have been carried out to test this theory [2]. Measurement of beam halo is particularly problematic for faint halos, where light from the intense core obscures the optical image of the halo. In this paper, we present a new diagnostic for high-dynamic range halo measurements based on adaptive masking of the beam core [3]. We also present the design of an experiment to study halo formation from envelope mismatch for beams spanning a wide range of intensities on the University of Maryland Electron Ring (UMER) [4]. [1] R. Gluckstern, Phys. Rev. Lett., vol.73, 1994. [2] C. Allen, Phys. Rev. Lett. Vol 89, 1998 [3] H. Zhang, et al., Proc of PAC11. [4] R.A. Kishek, these proceedings.

TUO1A04	Plasma Traps for Space-charge Studies: Status and Perspectives	plasma, ion, resonance, laser	235
	H. Okamoto, K. Fukushima, H. Higaki, K. Ito, K. Moriya, T. Okano, S. Yamaguchi HU/AdSM, Higashi-Hiroshima, Japan M. Endo Hiroshima University, Higashi-Hiroshima, Japan A. Mohri Kyoto University, Graduate School of Human and Environmental Studies, Kyoto, Japan
	Funding: Work supported in part by a Grant-in-Aid for Scientific Research, Japan Society for the Promotion of Science. The beam physics group of Hiroshima University has developed non-neutral plasma traps dedicated solely to a wide range of beam dynamics studies. Those unique experimental tools approximately reproduce, in the laboratory frame, a many-body Coulomb system that is physically equivalent to a charged-particle beam observed in the center-of-mass frame. We have designed and constructed two different types of traps that employ either a radio-frequency electric quadrupole field or an axial magnetic field for transverse particle confinement. The former type is commonly referred to as "linear Paul trap" and the latter as "Penning trap". At present, three Paul traps and one Penning trap are operational while a new Penning trap for beam halo experiments is under construction. Each of these compact experimental facilities consists of a trap, many power supplies, a vacuum system, a computer control system, etc., and is called "S-POD (Simulator for Particle Orbit Dynamics)". S-POD is particularly useful for fundamental studies of high-intensity and high-brightness hadron beams. We here report on recent experimental outputs from S-POD and also briefly describe some future plans.
	Slides TUO1A04 [7.790 MB]

TUO1B04	Beam Loss Control for the Fermilab Main Injector	radiation, collimation, injection, booster	264
	B.C. Brown Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. From 2005 through 2012, the Fermilab Main Injector provided intense beams of 120 GeV protons to produce neutrino beams and antiprotons. Hardware improvements in conjunction with improved diagnostics allowed the system to reach sustained operation at ~400 kW beam power. Losses were at or near the 8 GeV injection energy where 95\% beam transmission results in about 1.5 kW of beam loss. By minimizing and localizing loss, residual radiation levels fell while beam power was doubled. Lost beam was directed to either the collimation system or to the beam abort. Critical apertures were increased while improved instrumentation allowed optimal use of available apertures. We will summarize the impact of various loss control tools and the status and trends in residual radiation in the Main Injector.
	Slides TUO1B04 [1.356 MB]

TUO3B02	Beam Dynamics of the ESS Superconducting Linac	linac, cavity, proton, emittance	278
	M. Eshraqi, H. Danared, R. Miyamoto ESS, Lund, Sweden
	The European Spallation Source, ESS, uses a linear accelerator to deliver the high intensity proton beam to the target station. The nominal beam power is 5 MW at an energy of 2.5 GeV. The superconducting part covers more than 95\% of the energy gain and 90\% of the length. The beam dynamics criteria applied to the design of the superconducting part of the linac including the frequency jump at a medium energy of 200 MeV as well as the beam dynamics performance of this structure are described in this paper.
	Slides TUO3B02 [4.406 MB]

TUO3B04	End to End Beam Dynamics and Design Optimization for CSNS Linac	DTL, lattice, linac, rfq	286
	J. Peng, S. Fu, H.C. Liu, H.F. Ouyang, X. Yin IHEP, Beijing, People's Republic of China
	The China Spallation Neutron Source (CSNS) will use a linear accelerator delivering a 15mA beam up to 80MeV for injection into a rapid cycling synchrotron (RCS). Since each section of the linac was determined individually, a global optimization based on end-to-end simulation results has refined some design choices, including the drift-tube linac (DTL) and the medium energy beam transport (MEBT). The simulation results and reasons for adjustments are presented in this paper.
	Slides TUO3B04 [1.131 MB]

TUO3C04	Beam Loss Mitigation in the Oak Ridge Spallation Neutron Source	linac, DTL, neutron, injection	329
	M.A. Plum ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. The Oak Ridge Spallation Neutron Source (SNS) accelerator complex routinely delivers 1 MW of beam power to the spallation target. Due to this high beam power, understanding and minimizing the beam loss is an ongoing focus area of the accelerator physics program. In some areas of the accelerator facility the equipment parameters corresponding to the minimum loss are very different from the design parameters. In this presentation we will summarize the SNS beam loss measurements, the methods used to minimize the beam loss, and a compare the design vs. the loss-minimized equipment parameters.
	Slides TUO3C04 [4.617 MB]

THO1A02	Effects of Magnetic Field Tracking Errors and Space Charge on Beam Dynamics at CSNS/RCS	space-charge, simulation, resonance, lattice	484
	S.Y. Xu, N. Wang, S. Wang IHEP, Beijing, People's Republic of China
	The China Spallation Neutron Source (CSNS) is an accelerator-based facility. It operates at 25 Hz repetition rate with an design beam power of 100 kW. CSNS consists of a 1.6-GeV Rapid Cycling Synchrotron (RCS) and a 80-MeV linac. The lattice of the CSNS/RCS is triplet based four-fold structure. The preferred working points of CSNS/RCS are (4.86, 4.78) which can avoid the major low-order structure resonances. But because of the chromatic tune shift, space-charge incoherent tune shift and the tune shift caused by magnetic field tracking errors between the quadrupoles and the dipoles, some structure resonances are unavoidable. The chromaticity, space charge effects and magnetic field tracking errors can also induce beta function distortion, and influence the transverse acceptance and the collimation efficiency of the collimation system. In this paper we show results of space-charge simulations introducing magnetic field tracking errors and discuss the combined effects of chromaticity, magnetic field tracking errors and space charge on the beam dynamics for CSNS/RCS.
	Slides THO1A02 [1.613 MB]

THO3C05	Fiber Based BLM System Research and Development at CERN	photon, radiation, beam-losses, electron	596
	S. Mallows The University of Liverpool, Liverpool, United Kingdom E.B. Holzer, S. Mallows, J.W. van Hoorne CERN, Geneva, Switzerland
	The application of a beam loss measurement (BLM) system based on Cherenkov light generated in optical fibers to a linear accelerator with long bunch trains is currently under investigation at CERN. In the context of the Compact Linear Collider (CLIC) study, the machine protection role of the BLM system consists of its input to the \lqnext cycle permit\rq. In between two cycles it is determined whether it is safe to commit the machine for the next cycle. A model for light production and propagation has been developed and validated with beam measurements. Monte Carlo simulations of loss scenarios established the suitability in terms of sensitivity and dynamic range. The achievable longitudinal position resolution of the system, considering that the bunch trains and the optical fiber length are comparable in size is discussed.
	Slides THO3C05 [3.846 MB]

Paper

Title

Other Keywords

Page

Planning for Experimental Demonstration of Transverse Emittance Transfer at the GSI UNILAC through Eigen-emittance Shaping

emittance, coupling, simulation, scattering

57

C. Xiao, O.K. Kester
IAP, Frankfurt am Main, Germany
L. Groening
GSI, Darmstadt, Germany

The minimum transverse emittances achievable in a beam line are determined by the two transverse eigen-emittances of the beam. For vanishing interplane correlations they are equal to the well-know rms-emittances. Eigen-emittances are constants of motion for all symplectic beam line elements, i.e. (even tilted) linear elements. To allow for rms-emittance transfer, the eigen-emittances must be changed by applying a non-symplectic action to the beam, preferably preserving the 4d-rms-emittance. This contribution will introduce the concept for eigen-emittance shaping and rms-emittance transfer at an ion linac. A path towards the experimental demonstration of the concept at the GSI UNILAC is presented.

MOP211

1-MW Beam Operation Scenario in the J-PARC RCS

injection, emittance, lattice, controls

68

H. Hotchi, H. Harada, N. Hayashi, M. Kinsho, P.K. Saha, Y. Shobuda, F. Tamura, K. Yamamoto, M. Yamamoto, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Irie
KEK, Ibaraki, Japan

The injection energy of the J-PARC RCS will be upgraded from 181 MeV to 400 MeV in the 2013 summer-autumn period. With this upgraded injection energy, we are to aim for 1 MW design output beam power. In this paper, we discuss beam dynamics issues for the 1 MW beam operation and their possible solutions.

MOP220

Local Compensation-rematch for Major Element Failures in the C-ADS Accelerator

cavity, solenoid, emittance, focusing

102

B. Sun, Z. Li, J.Y. Tang, F. Yan
IHEP, Beijing, People's Republic of China

In order to achieve the required reliability and availability for the C-ADS accelerator, a fault tolerance design is pursued. The effects of cavity failure in different locations have been studied and the schemes of compensation by means of local compensation have been investigated. After one cavity failure, by adjusting the settings of the neighboring cavities and the focusing elements to make sure that the Twiss parameters and energy are approximately recovered to that of the nominal ones at the matching point. We find the normalized RMS emittance and emittances including 99.9% and 100% particles have no obvious growth after applying the compensation with the RMS rematching in each section of the main linac. However, the conclusions above are drawn from the simulation results with the TraceWin code, which doesn't consider the phase difference. A code based on Matlab is under developing. By applying the code on the cavity failure in the middle part of spoke021 section, a fully compensated scheme with good dynamics results is obtained. The space charge effect is still not implanted in the code, and further study and optimization of the code will be performed in the next step.

MOP229

Design of the MEBT1 for C-ADS Injector II

emittance, DTL, rfq, simulation

115

H. Jia, Y. He, S.C. Huang, C.L. Luo, M.T. Song, Y.J. Yuan, X. Zhang
IMP, Lanzhou, People's Republic of China

The MEBT1 of Chinese ADS Injector II is described. It transports a 2.1 MeV, 10 mA CW proton beam through a series of 7 quadruples and two buncher cavities from the RFQ to the superconducting DTL. For emittance preservation, a compact mechanical design is required. Details of the beam dynamics and mechanical design will be given.

MOP235

Medium Energy Beam Transport Design Update for ESS

cavity, linac, DTL, rfq

128

I. Bustinduy, F.J. Bermejo, A. Ghiglino, O. González, J.L. Muñoz, I. Rodríguez, A. Zugazaga
ESS Bilbao, Bilbao, Spain
B. Cheymol, M. Eshraqi, R. Miyamoto
ESS, Lund, Sweden
J. Stovall
CERN, Geneva, Switzerland

The major challenge of this part of the accelerator is to keep a high quality beam, with a pulse well defined in time, a low emittance and a minimized halo, so that the beam losses downstream the linac be limited and the overall ESS reliability be maximized. In order to minimize beam loss at high energy linac, and the consequent activation of components, a fast chopping scheme is presented for the medium energy beam transport section (MEBT). The considered versatile MEBT is being designed to achieve four main goals: First, to contain a fast chopper and its correspondent beam dump, that could serve in the commissioning as well as in the ramp up phases. Second, to serve as a halo scraping section by means of two adjustable blades. Third, to measure the beam phase and profile between the RFQ and the DTL, along with other beam monitors. And finally, to match the RFQ output beam characteristics to the DTL input both transversally and longitudinally. For this purpose a set of ten quadrupoles is used to match the beam characteristics transversally, combined with two 352.2 MHz buncher cavities, which are used to adjust the beam in order to fulfill the required longitudinal parameters.

MOP238

Beam Position Monitor System of the ESS Linac

linac, LLRF, controls, target

133

H. Hassanzadegan, A. Jansson
ESS, Lund, Sweden
A.J. Johansson
Lund University, Lund, Sweden

The pulsed ESS linac will include about 100 BPMs, mostly with a European XFEL style button design, 6 BPMs with a special design for the Medium Energy Beam Transport, as well as 8 stripline BPMs foreseen for the Drift Tubes. The required accuracy and resolution of the position measurement are 100 μm (rms) and 20 μm (rms) respectively with the 50 mA 2.86 ms nominal pulse. In addition to the position measurement, the BPM system needs to measure the beam phase in the nominal pulse as well as several diagnostics pulse modes with a minimum duration and intensity of 5 μs and 5 mA respectively. After a study of the possible electronics platforms, MTCA.4 is now considered as the main prototyping platform for the high performance sub-systems at ESS. It is foreseen to prototype a Rear Transition Module for IQ-based RF signal measurements intended for both the BPM and LLRF systems. The requirements and specifications of the BPM system are presented and the plan for the continuation of the project is described in this paper.

MOP243

Experimental Results of Beam Halo at IHEP

simulation, rfq, space-charge, beam-transport

151

H.F. Ouyang, T. Huang, J. Li, J. Peng, T.G. Xu
IHEP, Beijing, People's Republic of China

Space-charge forces acting in mismatched beams have been identified as a major cause of beam halo. In this paper, we describe the beam halo experimental results in a FODO beam line at IHEP. With this beam transport line, experiments are firstly carried out to determine the main beam parameters at the exit of a RFQ with intense beams, and then the measured beam profiles at different positions are compared with the multi-particle simulation profiles to study the formation of beam halo. The maximum measured amplitudes of the matched and mismatched beam profiles agreed well with simulations. Details of the experiment will be presented.

MOP260

Beam Halo Measurements using Adaptive Masking Methods and Proposed Recent Halo Experiment

injection, space-charge, diagnostics, simulation

215

H.D. Zhang, B.L. Beaudoin, S. Bernal, R.B. Fiorito, R.A. Kishek, K. Řežaei, A.G. Shkvarunets
UMD, College Park, Maryland, USA

Beam halo is a common phenomenon in particle beams, especially for modern, advanced accelerators where high beam intensities lead to strong space charge. Halo is generally understood as a population of particles that do, or will, reach large transverse radii relative to a more intense, centralized beam core. It is associated with emittance growth, beam quality degradation and particle loss. The particle-core model [1] is commonly used to describe halo formation as the result of a parametric resonance due to envelope mismatch. Few experiments have been carried out to test this theory [2]. Measurement of beam halo is particularly problematic for faint halos, where light from the intense core obscures the optical image of the halo. In this paper, we present a new diagnostic for high-dynamic range halo measurements based on adaptive masking of the beam core [3]. We also present the design of an experiment to study halo formation from envelope mismatch for beams spanning a wide range of intensities on the University of Maryland Electron Ring (UMER) [4].
[1] R. Gluckstern, Phys. Rev. Lett., vol.73, 1994.
[2] C. Allen, Phys. Rev. Lett. Vol 89, 1998
[3] H. Zhang, et al., Proc of PAC11.
[4] R.A. Kishek, these proceedings.

TUO1A04

Plasma Traps for Space-charge Studies: Status and Perspectives

plasma, ion, resonance, laser

235

H. Okamoto, K. Fukushima, H. Higaki, K. Ito, K. Moriya, T. Okano, S. Yamaguchi
HU/AdSM, Higashi-Hiroshima, Japan
M. Endo
Hiroshima University, Higashi-Hiroshima, Japan
A. Mohri
Kyoto University, Graduate School of Human and Environmental Studies, Kyoto, Japan

Funding: Work supported in part by a Grant-in-Aid for Scientific Research, Japan Society for the Promotion of Science.
The beam physics group of Hiroshima University has developed non-neutral plasma traps dedicated solely to a wide range of beam dynamics studies. Those unique experimental tools approximately reproduce, in the laboratory frame, a many-body Coulomb system that is physically equivalent to a charged-particle beam observed in the center-of-mass frame. We have designed and constructed two different types of traps that employ either a radio-frequency electric quadrupole field or an axial magnetic field for transverse particle confinement. The former type is commonly referred to as "linear Paul trap" and the latter as "Penning trap". At present, three Paul traps and one Penning trap are operational while a new Penning trap for beam halo experiments is under construction. Each of these compact experimental facilities consists of a trap, many power supplies, a vacuum system, a computer control system, etc., and is called "S-POD (Simulator for Particle Orbit Dynamics)". S-POD is particularly useful for fundamental studies of high-intensity and high-brightness hadron beams. We here report on recent experimental outputs from S-POD and also briefly describe some future plans.

Slides TUO1A04 [7.790 MB]

TUO1B04

Beam Loss Control for the Fermilab Main Injector

radiation, collimation, injection, booster

264

B.C. Brown
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
From 2005 through 2012, the Fermilab Main Injector provided intense beams of 120 GeV protons to produce neutrino beams and antiprotons. Hardware improvements in conjunction with improved diagnostics allowed the system to reach sustained operation at ~400 kW beam power. Losses were at or near the 8 GeV injection energy where 95\% beam transmission results in about 1.5 kW of beam loss. By minimizing and localizing loss, residual radiation levels fell while beam power was doubled. Lost beam was directed to either the collimation system or to the beam abort. Critical apertures were increased while improved instrumentation allowed optimal use of available apertures. We will summarize the impact of various loss control tools and the status and trends in residual radiation in the Main Injector.

Slides TUO1B04 [1.356 MB]

TUO3B02

Beam Dynamics of the ESS Superconducting Linac

linac, cavity, proton, emittance

278

M. Eshraqi, H. Danared, R. Miyamoto
ESS, Lund, Sweden

The European Spallation Source, ESS, uses a linear accelerator to deliver the high intensity proton beam to the target station. The nominal beam power is 5 MW at an energy of 2.5 GeV. The superconducting part covers more than 95\% of the energy gain and 90\% of the length. The beam dynamics criteria applied to the design of the superconducting part of the linac including the frequency jump at a medium energy of 200 MeV as well as the beam dynamics performance of this structure are described in this paper.

Slides TUO3B02 [4.406 MB]

TUO3B04

End to End Beam Dynamics and Design Optimization for CSNS Linac

DTL, lattice, linac, rfq

286

J. Peng, S. Fu, H.C. Liu, H.F. Ouyang, X. Yin
IHEP, Beijing, People's Republic of China

The China Spallation Neutron Source (CSNS) will use a linear accelerator delivering a 15mA beam up to 80MeV for injection into a rapid cycling synchrotron (RCS). Since each section of the linac was determined individually, a global optimization based on end-to-end simulation results has refined some design choices, including the drift-tube linac (DTL) and the medium energy beam transport (MEBT). The simulation results and reasons for adjustments are presented in this paper.

Slides TUO3B04 [1.131 MB]

TUO3C04

Beam Loss Mitigation in the Oak Ridge Spallation Neutron Source

linac, DTL, neutron, injection

329

M.A. Plum
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
The Oak Ridge Spallation Neutron Source (SNS) accelerator complex routinely delivers 1 MW of beam power to the spallation target. Due to this high beam power, understanding and minimizing the beam loss is an ongoing focus area of the accelerator physics program. In some areas of the accelerator facility the equipment parameters corresponding to the minimum loss are very different from the design parameters. In this presentation we will summarize the SNS beam loss measurements, the methods used to minimize the beam loss, and a compare the design vs. the loss-minimized equipment parameters.

Slides TUO3C04 [4.617 MB]

THO1A02

Effects of Magnetic Field Tracking Errors and Space Charge on Beam Dynamics at CSNS/RCS

space-charge, simulation, resonance, lattice

484

S.Y. Xu, N. Wang, S. Wang
IHEP, Beijing, People's Republic of China

The China Spallation Neutron Source (CSNS) is an accelerator-based facility. It operates at 25 Hz repetition rate with an design beam power of 100 kW. CSNS consists of a 1.6-GeV Rapid Cycling Synchrotron (RCS) and a 80-MeV linac. The lattice of the CSNS/RCS is triplet based four-fold structure. The preferred working points of CSNS/RCS are (4.86, 4.78) which can avoid the major low-order structure resonances. But because of the chromatic tune shift, space-charge incoherent tune shift and the tune shift caused by magnetic field tracking errors between the quadrupoles and the dipoles, some structure resonances are unavoidable. The chromaticity, space charge effects and magnetic field tracking errors can also induce beta function distortion, and influence the transverse acceptance and the collimation efficiency of the collimation system. In this paper we show results of space-charge simulations introducing magnetic field tracking errors and discuss the combined effects of chromaticity, magnetic field tracking errors and space charge on the beam dynamics for CSNS/RCS.

Slides THO1A02 [1.613 MB]

THO3C05

Fiber Based BLM System Research and Development at CERN

photon, radiation, beam-losses, electron

596

S. Mallows
The University of Liverpool, Liverpool, United Kingdom
E.B. Holzer, S. Mallows, J.W. van Hoorne
CERN, Geneva, Switzerland

The application of a beam loss measurement (BLM) system based on Cherenkov light generated in optical fibers to a linear accelerator with long bunch trains is currently under investigation at CERN. In the context of the Compact Linear Collider (CLIC) study, the machine protection role of the BLM system consists of its input to the \lqnext cycle permit\rq. In between two cycles it is determined whether it is safe to commit the machine for the next cycle. A model for light production and propagation has been developed and validated with beam measurements. Monte Carlo simulations of loss scenarios established the suitability in terms of sensitivity and dynamic range. The achievable longitudinal position resolution of the system, considering that the bunch trains and the optical fiber length are comparable in size is discussed.

Slides THO3C05 [3.846 MB]